NIR absorbing ferrocenyl perylenediimide-based donor-acceptor chromophores

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Perylenediimides (PDIs) are versatile chromophores with tunable electronic properties.
• Ferrocene and tetracyanobuta-1,3-diene (TCBD) units can be incorporated to modify PDI characteristics.
• Donor-acceptor (D-A) systems are crucial for developing advanced functional materials.

Purpose of the Study:

• To design and synthesize novel ferrocenyl-functionalized PDI derivatives.
• To investigate the impact of varying ferrocenyl and TCNE group numbers on material properties.
• To explore the photophysical, thermal, electrochemical, and spectroelectrochemical behavior of these new compounds.

Main Methods:

• Palladium-catalyzed Sonogashira cross-coupling for synthesis.
• Thermally activated [2 + 2] cycloaddition-retroelectrocyclization ([CA-RE]) reaction.
• Spectroscopic (absorption, electrochemistry, spectroelectrochemistry) and computational analyses.

Main Results:

• Successful synthesis of ferrocenyl-PDI-TCBD derivatives (1-5) in good yields.
• Di-substituted derivatives (3-5) showed bathochromic shifts due to extended π-conjugation.
• Electrochemical analysis revealed multiple reduction waves, indicative of acceptor units.
• Spectroelectrochemistry demonstrated visible-to-near-infrared (NIR) spectral shifts upon redox changes.
• Computational studies confirmed strong D-A interactions with electron density localized on ferrocene (HOMO) and PDI-TCBD (LUMO).

Conclusions:

• The synthesized ferrocenyl-PDI-TCBD compounds exhibit tunable photophysical and electrochemical properties.
• Extended π-conjugation and D-A interactions are key to their observed spectral shifts.
• These materials show promise for applications in near-infrared absorbing materials and optoelectronics.